1. Field of the Invention
The present invention relates to a bearing module for a vacuum pump having a rapidly rotatable shaft, with the bearing module including a rolling bearing for supporting rotatably the shaft, and a reservoir for a lubricant having an element forming a sliding contact with a delivery structure supported on the shaft for delivery of the lubricant in the rolling bearing under action of centrifugal forces generated during rotation of the shaft.
2. Description of the Prior Art
Despite advances in the vacuum technology, it is very important, in particular for rapidly rotatable shafts, to insure delivery of lubricant to rolling bearings which rotatably support the shafts. The lubricant generally undergoes changes and becomes contaminated with impurities. Despite lubrication, the rolling bearings are still subjected to wear because of friction. Therefore, both the lubricant and the rolling bearings should be replaced from time to time.
According to the state of the art, conventionally, there is provided a reservoir for lubricant in which the lubricant is stored as in a sponge. The rolling bearing is placed on a shaft and is secured to a housing part, together with a ring of a flexible material, with a threaded ring. At a side of the shaft remote from the rolling bearing, the reservoir, which surrounds the shaft end, is arranged. Under the action of centrifugal forces, the lubricant is delivered in the bearing and drips therefrom under the gravity force back into reservoir.
For proper functioning, the degree of preload of the material of the above-mentioned flexible ring is very important. One of the problems of the solution according to the state of the art consists in that the preload should be precisely adjusted after replacement of the bearing in the pump in which the shaft support arrangement is used. This makes servicing of the pumps more difficult. Moreover, the gravity force may be insufficient for returning the lubricant into the reservoir, as the gravity field of the earth depends on the orientation of the pump in space. To insure a reliable circulation of the lubricant, expensive constructions are used in the state of the art. E.g., German Publication DE-A-103 21 326 discloses an expensive lubricant feeding device with lubricant pumps. The device reliably operates only with delivery of a large amount of lubricant.
Accordingly, an object of the present invention is to provide an arrangement for delivery lubricant to a bearing and which is constructively simple and can be used in different installation positions.